1. Field of the Invention
The present invention relates to drive couplings.
2. Background and Related Art
Drive couplings are used in a wide variety of applications. Some examples of drive couplings include chain couplings, disc couplings, doughnut couplings, universal joints or clutches. Drive couplings are typically used to transmit drive from one shaft to another shaft. The shafts may be formed with the drive coupling or they may be connectable to the drive coupling.
In some applications, the equipment being driven by a drive arrangement may be susceptible to sudden shock loads. For example, large multi head grass and scrub cutting machines (termed rotary cutters or slashers) utilize heavy (16 mm to 19 mm thick) (⅝″ to ¾″ thick) cutting blades. To achieve overlap between cutters, the gear boxes which are connected in series by power take off drive shafts are timed so that the blades intersect.
These machines are prone to serious gear box and drive shaft failure. For example, when one individual cutter strikes an obstruction, cumulative forces from the tractor power source, combined with the flywheel effect (inertia) from all other gear boxes and cutting heads on the machine are transmitted to the individual gear box and shaft coupling involved in the incident.
Standard friction disc type safety clutches cannot be used on these machines, as the cutting blades can only be paused for a few degrees of rotation before contact occurs with adjacent cutting blades.
The most common method of coupling these gear boxes is via chain couplings, disc couplings, doughnut couplings or universal joints. None of these devices provide any predetermined rotational shock relief to transmissions.